Automatic tube cleaner for ultraviolet fluid (water) sterilizer

ABSTRACT

A circular cleaning device which scours the external surface of an ultraviolet radiation tube, which acts as a radiation source for bacteria kill in ultraviolet radiation fluid sterilizers, removes deposits, which precipitate out of the sterilizable fluid, from the external surface of the ultraviolet radiation tube, or its surrounding shield, and thereby sustains the emanation of high intensity radiation flux from the tube into the fluid which is to be sterilized.

United States Patent Free Sept. 9, 1975 [54] AUTOMATIC TUBE CLEANER FOR3,336,099 8/1967 Czulak ct al. 21/102 R ULTRAVIOLET FLUID (WATER)3,456,107 7/1969 Robertson 21/102 R 3,462,597 8/1969 Young 21/102 RSTERILIZER 3,562,520 2/1971 Hippen 21/102 R V2 v [75] Inventor 22: 1?West mower FOREIGN PATENTS OR APPLICATIONS 1,065,985 9/1959 German21/102 R [73] Assignee: Naturvard Research (Canada) Ltd., y

Vancouver Canada Primary ExaminerBarry S. Richman [22] Filed: Oct. 10,1973 Assistant ExaminerBradley R. Garris Attorney, Agent, orFirm-Finnegan, Henderson, [211 App! 404927 Farabow & Garrett [30]Foreign Application Priority Data 57 ABSTRACT Nov. 20, 1972 Canada156920 A circular cleaning device which ou the e t nal surface of anultraviolet radiation tube, which acts as [52] Cl 21/102 21/5.4 22254 aradiation source for bacteria kill in ultraviolet radia- 2 tion fluidsterilizers, removes deposits, which precipig A6hlL 5 g g g i g? tateout of the sterilizable fluid, from the external surl 0 mm 43 face ofthe ultraviolet radiation tube, or its surrounding shield, and therebysustains the emanation of high intensity radiation flux from the tubeinto the fluid [56] UNITE S S TZ F ES SZiENTS which is to be sterilized.3,061,721 10/1962 Brcnncr 21/102 R 6 Drawing Figures -...-o00o o o o q o.uutilOOOO 1 0000 INFLOW PATENTED SE? 975 sum 2 0f 2 AUTOMATIC TUBECLEANER FOR ULTRAVIOLET FLUID (WATER) STERILIZER BACKGROUND OF THEINVENTION 1. Field of the Invention v This invention relates to acleaning device for fluid, particularily, water sterilizers. Q

More particularly, the present invention relates to a cleaning de vicefor cleaning the outside surface of a protective sheath of a radiationtubeof an ultraviolet radiation water sterilizer or the like, whereinthe sterilizer employs a longitudinal ultraviolet radiation tube as asource of ultraviolet radiation or flux.

2. Description of the Prior Art I v Water sterilizers may employultraviolet .radiation tubes as a source of flux for the creation ofultraviolet radiation, and usually have a longitudinal ultraviolettube,"suspended coaxially along the axis of a cylindrical sterilizationchamber. The water which is to be sterilized flows from one end of thecylinder (usually the bottom) in a vortex-like manner, to the other endof the cylinder (usually the top) such that a mean capture time of thefluid within the chamber is sufficient, in relation to the magnitude ofthe flux created by the ultraviolet radiation source, that a bacteriastat fluid is obtained at the outflow of the sterilization cylinder.When this bacteria stat condition is achieved, a kill is saidtohave'been imparted to the bacteria suspended in the fluid; that is, allthe bacteria is killed.

It is knownthat the bacteria stat condition can be achieved fora fluidand in particular water, when the same is subjected to a minimumultraviolet flux dose at a certain frequency, as those skilled in theart will know. It is also known that the mean resident time of a fluidwithin the sterilization chamber must be increased-to maintain abacteria stat dose of flux as a result of mineral deposits forming onthe outside surface of the ultraviolet radiation source tube,ormoreaccurately, the eircumscribing protective sheath thereof, when asheath is employed; as mineral deposits have a tendency to absorb theultraviolet radiation. It is further known that a scraping device may beemployed to scrape mineral deposits off the sheath, but such prior artdevices suffer from such disadvantages as they have to be humanallyactivated with the appended result that a human may forget to do thesame and that fluid does not obtain the bacteria stat dose; or, furtherthat such prior art devices are not sufficiently efficient tosignificaiitly 'clea n themincral deposits-away to sustain the high fluxintensity of the radiation penetrating through the sheath and hence intothe fluid to be sterilized.

These deficiencies of the prior art have been avoided somewhat by'increasing the mean resident time of the fluid flowing through thesterilization chamber, but this reduces the-rate or the volume of fluidflow and hence decreases the sterilization efficiency of the sterilizeras well as having its effect on increase manufacturing and operatingcosts. e

. SUMMARYOF THE lNVENTlON v The invention,' therefore, contemplates anefficicnt cleaning device to scrape mineral and other deposits from thesurrounding'protcctive surface of an ultraviolet radiation tube. thedevice being activated by'the combined effect of the fluid flowthroughthe chamber cleaning device itself. when flow stops.

The cleaning device also contemplates providing a tight piston-typearrangement in the sterilizer between the outer sterilization wall andthe inner protective sheath so as to ensure adequate scraping of thedeposits from the protective surface of the sheath, whereupon high fluxintensities into the fluid can be sustained with minimum resident timeof the fluid in the sterilizer for akill.

. The invention, therefore, contemplates in combination a liquidsterilization cylinder having an inner wall whichdefines a chamber andpositioned in said chamher a coaxially-longitudinal located source ofultraviolet 'radiation' disposed behind an ultraviolet transmissivecylindrical sheath protective, a cleaning device adapted to pass to andfro within the chamber, during flow and non-flow of the liquid to besterilized, characterized in that the cleaning device comprises:

a. a first ring-like member having an orifice therein through which aliquid may flow; 1 Y

b. a flexible inner member attached to and disposed radially inward ofthe first ring-like member with a segment of its inner margin disposedon the locus of their circumference of a circle having a radius lessthan the exterior diameter of said sheath such that the segmentbiasingly urges againstthe said ultraviolet transmissive cylindricalsheath;

c. a flexible resilient outer member attached to and disposed radiallyoutward of the first ring-like member and having its outer circumferencebiasly urged against the inner wall of the sterilization cylinderwhereby the weight of the cleaning device, during nonfiow of the fluid,causes the cleaning device to fall whence the inner member scrapes theultraviolet transmissive cylindrical sheath again to clean said sheath,and wherein during such flow orifice in said first ringlike memberpermits fluid to pass from one side of the cleaning device to the otherand hence through the said chamber.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will now bedescribed by way of example with reference to the embodiment to theaccompanying drawing in which:

P16. 1 is a perspective view of a portion of a particularily, a watersterilization chamber the embodiments of the invention.

FIGS. 2 and 3 are longitudinal sections for explanation, showing theprofile of the cleaning device during flow and non-flow fluidconditions.

FIG. 4 is a plan view of the cleaning device.

FIG. 5 is a section along lines V-V of FIG. 4.

FIG. 6 is an expanded section along lines Vl-Vl of FIG. 4.

fluid, employing DESCRIPTION OF THE PREFERRED EMBODlMENT Referring toFlG. 1 afluid, particularily water, steril-. ization chamber I0 includesa hollow cylindrical chamber 11 disposing coaxially to its innerlongitudinal axis a protective exterior surface 52 of a circumseribingfused silica glass sheath 53 within which is disposed a longitudinalradiation source such as an ultra-violet lamp (not shown). The sheath ofsilica glass permits transmission of ultra-violet radiation into theregion between the sheath s3 and the interior wall of thechamsterilized, for

flexible metal membrane 15, also'radiation resistent,

and'capable; of providing a scraping action against the protectivesurface 52"while at thesame time retaining a reasonably good water tightseal between-the metal ring 13 and surface 52.-The metalring 13preferably is in two halves, 13a-and 13b, referring to FIG. 5, joinedtogether by appropriate. means (not shown) sandwiching the membranes 14and 15 betweenthem; Small holes or;orifices 16 are drilled through themetal annulus 13 symmetrically about .to. allow the passage of water 54across the cleaner throughthese. holes. The materials of construction ofthe-two membranes 14 and 15 and of the metal ring 13 all require carefulchoice as the effective weight of the cleaner 12 is important as is theflex. characteristics of the membrane 15 as will now be described. t"

In operation the fluids54 which is to be sterilized flows. into; thebottom of the chamber 11 at. 22.and up in a vortex-like fashion throughthe cylinder to be discharged off. the top (not shown) as those skilledin the artwill know. With the water 54 flowing, since the cleaner 12provides a reasonably good seal across the water' flow region (onlyimperfections around the periphery of the membranes l4 and 15 and theplurality of holes 16 in the metal annulus 13 permittingwater-tob'y-pass the cleaner) pressure'builds upunderneath the cleaner"(FIG. 2)and .produces' a force, F attempting tolift the cleanerupward. Theseepage loss, L, reduces the forceto an actual force, F Resisting therise of the cleaner 12 are the weight, W, of the cleaner and thefrictional force of cylindrical wall f and of the protective surface52', f If -F is greater that these opposing forces the cleaner will riseand in doing so will scrape the protective surface .52 thus cleansingit. Gareful choice of the inner membrane 15 will determine thecleaningefficiency. It has been found that a brush-like texturedmembrane ofcomposite or plastic material is satisfactory. The cleaner 12may be made to rise strongly despite the losses L and the frictionalforces, f,, andfl, and the-cleaner weight, W.

'whiies the water 54 is flowing the cleaner 12-will be held at the topof the sterilizer 10. Assoon as the flow stops the cleaner l2will havethe force F removed (the only force holding the cleaner 12 at the top ofthe sterilizer when the cleaner is stationary) and the weight, W (seeFIG. 3) will tend to pull the cleaner 12 to the bottom of the sterilizer110. The forces resisting this movement are the fri'cti'onal'forces ofthe membranes l4 and on thecylindrical,.wall 11,f,,, and. on theprotective surface 52, f together with .the water trapped beneath thecleaner 12. However, the holes 16 through the metal annulus 13. willallow the water below the cleaner to seep through the cleaner 12 on itsdownward travel providing the Weight,v W, is great enough to overcomethe frictional forces andresistance caused by the water 'flow..t hroughthe holes 16;; the cleaning device 12 will move boldly downward'arid themembrane l-5 .will flex and agair'rscrape the protective When asterilization chamber-havingan inner diameter of three inches(7.62 cm.)with a protective sheath 53 having an outer diameter of one inch (2.54cm.) was used'it has'been found that the cleaning device cleaner 12could have the following dimensions.

Metal annulus '13 [innerdiameter 1 /2 inches (3.675

' cm.) outer'diameter 2 /2 inches (6.350 cm.)].

I Flexible annular membrane 15 [inner diameter Ma inch (2.225'Cmf) outerdiameter 1 /2 inches (3.675

cm.)].. i. Q.

Flexible membrane 1'4 [inner diameter 2 inches (6.350 cm.) outerdiameter 3% inches (7.937 cm.)]. 7 v 7 Diameter. of orifices 16 l/16inches (0.159 cm.).

Weight (W) of thecleaning device 12 approximatelyMa pound (226.8 gms.)

The embodiments of the invention in which an exclu sive property orprivilege is claimedare defined as follows: v

l. A liquid sterilization system comprising: a cylinder having liquidinlet and outlet means and having an inner wall which defines a chamberand positioned in said chamber a coaxially-longitudinallylocated sourceof ultraviolet radiation comprising a protectiveult-raviolet-transmissive, cylindrical sheath containing anultraviolet-radiation generating means, and, a cleaning device adaptedto pass to and fro within the chamber, during-flow and non-flow oftheliquid to be sterilized, characterized in that the cleaning devicecomprises:

- a. a first-ring-like member having an orifice, therein through which aliquid may flow;

a flexible inner member attached to and disposed radially inward of thefirst ring-like member with the inner periphery of said-innermemberbiasly urged against the said ultraviolet-transmissive, cy-

lindricalsheath;

c. a flexible resilient outer-member attached to and disposed radiallyoutward of the first ring-like member andl hav ing the outercircumference of "said outer member biasly urged against the inner "wallof the sterilization cylinder whereby, during a liquid flow conditio'n,the cleaning device is forced to rise within said chamber, and, during anon-flow condition of theliquid the weight of the cleaning device causesthe device to fall and whence, during each condition; the inner memberscrapes the ultraviolet-transmissive, cylindrical sheath, and therebycleans said sheath, and wherein during such flow conditions the orificein said first ring-v 7 like member permits liquid to pa'ssfrom one sideof the cleaningdevice to the other and hence through R the said chamber.

2. The system of claim 1 wherein the first ring-like member is a metalannulus.

3. The system ofclaim 1 wherein the flexible resilient outer member isasolidannulus composed, of a semirigid. rubber.. I

4. The system of claim 1 wherein the flexible inner member is asemi-rigid; plastic, ultraviolet-radiation resistant membrane.

5. The system-of claim 1 wherein the flexible inner member is composedof a-flexible sheet of metal.

member is a metal annulus.

11. The system of claim 9 wherein the flexible resilient outer member isa solid annulus composed of a semi-rigid rubber.

12. The system of claim 9 wherein the flexible inner member is asemi-rigid, plastic, ultraviolet-radiationresistant membrane.

13. The system of claim 2 wherein the flexible inner member is composedof a flexible sheet of metal.

1. A LIQUID STERILIZATION SYSTEM COMPRISING: A CYLINDER HAVING LIQUIDINLET AND OUTLET MEANS AND HAVING AN INNER WALL WHICH DEFINES A CHAMBERAN POSITIONED IN SAID CHAMBER A COAXIALLYLONGITUDINALLY LOCATED SOURCEOF ULTRAVIOLET RADIATION COMPRISING A PROTECTIVEULTRAVIOLET-TRANSMISSIVE, CYLINDRICAL SHEATH CONTAINING ANULTRAVIOLET-RADIATION GENERATING MEANS, AND, A CLEANING DEVICE ADAPTEDTO PASS TO AND FRO WITHIN THE CHAMBER, DURING FLOW AND NON-FLOW OF THELIQID TO BE SERILIZED, CHARACTERIZED IN THAT THE CLEANING DEVICECOMPRISES: A. A FIRST RING-LIKE MEMBER HAVING AN ORIFICE, THEREINTHROUGH WHICH A LIQUID MAY FLOW, B. A FLEXIBLE INNER MEMBER ATTACHED TOAND DISPOSED RADIALLY INWARD OF THE FIRST RING-LIKE MEMBER WITH THEINNER PERIPHERY OF SAID INNER MEMBER BIASLY URGED AGAINST THE SAIDULTRAVIOLET-TRANSMISSIVE, CYLINDRICAL SHEATH, C. A FLEXIBLE RESILIENTOUTER MEMBER ATTACHED TO AND DISPOSED RADIALLY OUTWARD OF THE FIRSTRING-LIKE MEMBER AND HAVING THE OUTER CIRCUMFERENCE OF SAID OUTER MEMBERBIASLY URGED AGAINST THE INNER WALL OF THE STERILIZATION CYLINDERWHEREBY, DURING A LIQUID FLOW CONDITION, THE CLEANING DEVICE IS FORCEDTO RISE WITHIN SAID CHAMBER, AND, DURING A NON-FLOLW CONDITION OF THELIQUID, THE WEIGHT OF THE CLEANING DEVICE CAUSES THE DEVICE TO FALL ANDWHENCE, DURING EACH CONDITION, THE INNER MEMBER SCRAPES THEULTRAVIOLET-TRANSMISSIVE, CYLINDRICAL SHEATH, AND THEREBY CLEANS SAIDSHEATH, AND WHEREIN DURING SUCH FLOW CONDITIONS THE ORIFICE IN SAIDFIRST RING-LIKE MEMBER PERMITS LIQUID TO PASS FROM ONE SIDE OF THECLEANING DEVICE TO THE OTHER AND HENCE THROUGH THE SAID CHAMBER.
 2. Thesystem of claim 1 wherein the first ring-like member is a metal annulus.3. The system of claim 1 wherein the flexible resilient outer member isa solid annulus composed of a semi-rigid rubber.
 4. The system of claim1 wherein the flexible inner member is a semi-rigid, plastic,ultraviolet-radiation resistant membrane.
 5. The system of claim 1wherein the flexible inner member is composed of a flexible sheet ofmetal.
 6. The system of claim 1 wherein the flexible inner member is anannulus with an inner diameter nominally less than the outer diameter ofsaid sheath.
 7. The system of claim 1 wherein the first ring-like memberhas a plurality of orifices circumferentially positioned in saidring-like member.
 8. The system of claim 7 wherein the flexible innermember is composed of a flexible sheet of metal.
 9. The system of claim1 wherein the first ring-like member has a plurality of orificesdisposed therein.
 10. The system of claim 9 wherein the first ring-likemember is a metal annulus.
 11. The system of claim 9 wherein theflexible resilient outer member is a solid annulus composed of asemi-rigid rubber.
 12. The system of claim 9 wherein the flexible innermember is a semi-rigid, plastic, ultraviolet-radiation-resistantmembrane.
 13. The system of claim 2 wherein the flexible inner member iscomposed of a flexible sheet of metal.